The present invention relates to fluidised bed combustors.
It has been found that during use of conventional fluidised bed combustors having heat exchange jackets for connection to external heating systems there is sometimes an inability to raise the bed temperature to the normal working level of about 850.degree. C. It is believed that this phenomenon is caused by the inability to limit the heat loss to the jacket from the combustor during warm-up and can lead to agglomeration and incomplete combustion in the fluidised bed.
The present invention is directed towards a fluidised bed combustor system which alleviates this problem by using a combustion chamber having a lined base portion to reduce heat removal during bed warm up and periods when the bed is slumped. Also the invention is directed towards a system for controlling the heat output of a fluidised bed combustor which avoids the need for the more usual techniques of load control such as bed temperature modulation and slumping of separate sections of the fluidised bed.